[PATCH 3.2 45/77] locking: Add WARN_ON_ONCE lock assertion

Ben Hutchings
2015-12-24T15:43:34Z

From: Peter Hurley <peter@hurleysoftware.com>

commit 9a37110d20c95d1ebf6c04881177fe8f62831db2 upstream.

An interface may need to assert a lock invariant and not flood the
system logs; add a lockdep helper macro equivalent to
lockdep_assert_held() which only WARNs once.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/linux/lockdep.h | 5 +++++
1 file changed, 5 insertions(+)

--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -342,6 +342,9 @@ extern void lockdep_trace_alloc(gfp_t ma
#define lockdep_depth(tsk) (debug_locks ? (tsk)->lockdep_depth : 0)

#define lockdep_assert_held(l) WARN_ON(debug_locks && !lockdep_is_held(l))
+#define lockdep_assert_held_once(l) do { \
+ WARN_ON_ONCE(debug_locks && !lockdep_is_held(l)); \
+ } while (0)

#else /* !LOCKDEP */

@@ -362,6 +365,7 @@ static inline void lockdep_on(void)
# define lockdep_trace_alloc(g) do { } while (0)
# define lockdep_init() do { } while (0)
# define lockdep_info() do { } while (0)
+
# define lockdep_init_map(lock, name, key, sub) \
do { (void)(name); (void)(key); } while (0)
# define lockdep_set_class(lock, key) do { (void)(key); } while (0)
@@ -391,6 +395,7 @@ struct lock_class_key { };
#define lockdep_depth(tsk) (0)

#define lockdep_assert_held(l) do { } while (0)
+#define lockdep_assert_held_once(l) do { (void)(l); } while (0)

#endif /* !LOCKDEP */